Brake control devices using electrical and electronic circuitry to apply electrical, hydraulic or pneumatic braking to trailer vehicles in response to sudden deceleration or sudden acceleration forces in the tractor or towing structure are generally well known. Initially such devices were mechanically associated with the brake system or pedal so that depression of the pedal tripped a brake actuator. Such systems involved an inherent lag and were responsive only to the application of brakes in the tractor or towing structure (motor vehicle in the case of travel trailers and the like). Accordingly, attempts were made to apply inertial sensing devices to the problem of sensing for braking of the towed vehicle so that the sensitivity of the system would be responsive to forces generated by the act of braking in the towing vehicle or other change in inertial balance. Such devices and circuits therefore are indicated, for example, in the U.S. Pat. Nos. 2,032,177 to J. W. Logan, Jr. and 3,779,612 to Hans Tschannen. In the copending U.S. patent applications Ser. No. 385,102 to Piettet et al. and Ser. No. 531,171 to Tomecek et al. are unidirectional inertial sensors for brakes in which a light beam is interrupted by a pendulum structure. None of these devices are as simple as the devices of the present invention and none use magnetic dampening and compactness as expressed herein. Many prior art sensors lack the resistance to false tripping by vertical impact forces as by washboard roads and chuckholes.
Accordingly, the principal object of the present invention is to provide a pendulum sensor pivotal from a fixed point and dampened by a magnet to control brakes in towed devices and in control of braking and swaying. A collateral object is to provide a sensor resistant to tripping on swaying or braking forces but insensitive to vertical forces and smooth wide curves.
Another object is to teach a highly compact construction for an inertial sensor for braking in which a light beam is interrupted and to reduce the weight and bulk therein.
Still another object is to provide an improved and less expensive pendulum sensor for braking systems which may be located in the tractor device or the towing device with minimum clearance problems for both brake control or sway control. In the omnidirectional variants of the present invention, a single pendulum is able to sense both sway and braking forces for control over braking. In the unidirectional variations, plural series connected of unidirectional structures faced at right angles to each other are used to achieve braking or sway control or both.
Other objects will be readily appreciated by those skilled in the art as the description proceeds.